83661021 has 6 divisors (see below), whose sum is σ = 120843710. Its totient is φ = 55774008.

The previous prime is 83661013. The next prime is 83661023. The reversal of 83661021 is 12016638.

It can be written as a sum of positive squares in only one way, i.e., 56475225 + 27185796 = 7515^2 + 5214^2 .

It is not a de Polignac number, because 83661021 - 2³ = 83661013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (83661023) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4647826 + ... + 4647843.

Almost surely, 2^83661021 is an apocalyptic number.

It is an amenable number.

83661021 is a deficient number, since it is larger than the sum of its proper divisors (37182689).

83661021 is a wasteful number, since it uses less digits than its factorization.

83661021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9295675 (or 9295672 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 83661021 is about 9146.6398748393. The cubic root of 83661021 is about 437.3620066565.

Adding to 83661021 its reverse (12016638), we get a palindrome (95677659).

The spelling of 83661021 in words is "eighty-three million, six hundred sixty-one thousand, twenty-one".